This invention relates to a rotational slide type mechanical pencil in which a slider holding a lead is retractable and extendable in and out of a mouth opening of the mechanical pencil body.
A rotation lead feeding type of mechanical pencil has been frequently used and is well known. However, the rotation lead feeding mechanical pencil has the following disadvantages:
(1) Both hands are required to hold the pencil to provide a lead at the mouth end of the mechanical pencil;
(2) An axial body member must be rotated, confirming an extending length of the lead;
(3) A new lead must be inserted from the mouth opening into the mechanical pencil to supply a new lead;
(4) Since a lead is liable to be broken in a new lead supply, a thin lead cannot be used.
Due to the above disadvantages, the rotation lead feeding type mechanical pencil is not used as often as it was several years ago. Instead, recently, a step-by-step knocking type mechanical pencil has been introduced and is frequently used. However, the knocking type mechanical pencil has the significant disadvantage in that the mechanism thereof deteriorates due to a knocking cap. In order to overcome this, a slide cap type mechanical pencil has been provided. However, the slide cap type mechanical pencil has also significant disadvantages since a reciprocatingly movable cap per se is moved forward and backward with every knock and the cap is contacted to the gripping hand making it difficult to handle it.
On the other hand, a rotation lead feeding type mechanical pencil is still used in parts of the world especially in Europe and the U.S. Some big companies therein still make the rotation lead feeding type because a rotation type has an image of a high class article. Also a rotation type of device despite its inherent disadvantages generally has a long service life.